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  1. #1

    Default Seeking advice on what type of pitch/ prop to use on a 1986 Mercury 50 hp outboard 2 stroke 4 cyl

    Hello, I am seeking advice on what type of prop to use for my boat, and will start with some info on my setup. It is not the original motor on the boat. It is a 1971 Mark Twain 16ft V-Sonic (Runabout) with a 1986 Mercury outboard 50 hp 2 stroke, and assuming 4cyl since it has four spark plugs. Weighs about 1760 lbs. according to an online site but, not sure if that is with or without the motor or if it is with the original motor. The hull is rated for a 125 hp so I'm guessing the stock motor was bigger. It has been a nice vintage work in progress but the rpm gauge and speedometer doesn't work so I have to use my phones gps. I have got it up to 24.2 mph by myself, 19.1 mph with two 230lb guys, and about 11-12 mph with another girl added (180lbs), and 10 or less with 4 people. This weight includes the 29D battery, 11 gallons of mixed gas, and other light weight items like life jackets etc.... I've been playing with the trim and all that and I believe I have it to the best of its ability. However, I noticed that the aluminum prop has a lot of chips in it and imperfections, not real sure if its bent or not, but it is a 10-3/8" 13Pitch triple blade. I was looking to replace it and wasn't sure if I should move up to a 14 or 15 Pitch to gain some speed. I feel like it should be moving slightly faster. Also, should I stay with the same diameter? Without knowing the WOT recommended range, or what my rpms are currently at, I sort of have to play it by ear, but don't want to bump my pitch up to high since it is a smaller power engine... Any suggestions or tips would be very helpful. Thanks!! Engine Model #: A100526 Prop #48 73136 A40 13P

  2. #2

    Default Re: Seeking advice on what type of pitch/ prop to use on a 1986 Mercury 50 hp outboard 2 stroke 4 cy

    IF any other information is needed please feel free to ask!

  3. #3
    Join Date
    Apr 2016
    Location
    barnegat NJ
    Posts
    2,707

    Default Re: Seeking advice on what type of pitch/ prop to use on a 1986 Mercury 50 hp outboard 2 stroke 4 cy

    If you feel a vibration at the helm prop could be bent,otherwise your good, You will need a tach to achieve WOT and the wot rpm specs,

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